Since their introduction, the number of services and features for cellular telephones has steadily increased. At first, these mobile devices operated on analog wireless networks that enabled voice communication and simple paging features. Later, digital wireless networks for cellular telephones were implemented to provide more advanced features for voice and data communication, such as encryption, caller identification and short message service (SMS) text messages. More recently, some cellular telephones enable the browsing of web pages on the Internet or other on-line services.
The functionality of cellular telephones has continued to increase and incorporate many of the features originally provided for in handheld electronic devices such as personal digital assistants (PDAs). Relatively simple PDA features such as keeping a list of contacts, a calendar, appointments, and the like have been generally integrated into recent cellular telephone models. However, a user has not been able to readily give or receive opinions with a cellular telephone. Typically, a cellular telephone user has to access a separate source to be able to express an opinion about an item or receive opinions regarding a particular item.